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Mechanism of the Oxidation of 3,3′,5,5′‐Tetramethylbenzidine Catalyzed by Peroxidase‐Like Pt Nanoparticles Immobilized in Spherical Polyelectrolyte Brushes: A Kinetic Study
Author(s) -
Gu Sasa,
Risse Sebastian,
Lu Yan,
Ballauff Matthias
Publication year - 2020
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201901087
Subject(s) - catalysis , polyelectrolyte , chemistry , nanoparticle , hydrogen peroxide , adsorption , reaction mechanism , reaction rate constant , reaction rate , chemical engineering , photochemistry , inorganic chemistry , kinetics , organic chemistry , physics , quantum mechanics , engineering , polymer
Experimental and kinetic modelling studies are presented to investigate the mechanism of 3,3′,5,5′‐tetramethylbenzidine (TMB) oxidation by hydrogen peroxide (H 2 O 2 ) catalyzed by peroxidase‐like Pt nanoparticles immobilized in spherical polyelectrolyte brushes (SPB−Pt). Due to the high stability of SPB−Pt colloidal, this reaction can be monitored precisely in situ by UV/VIS spectroscopy. The time‐dependent concentration of the blue‐colored oxidation product of TMB expressed by different kinetic models was used to simulate the experimental data by a genetic fitting algorithm. After falsifying the models with abundant experimental data, it is found that both H 2 O 2 and TMB adsorb on the surface of Pt nanoparticles to react, indicating that the reaction follows the Langmuir–Hinshelwood mechanism. A true rate constant k , characterizing the rate‐determining step of the reaction and which is independent on the amount of catalysts used, is obtained for the first time. Furthermore, it is found that the product adsorbes strongly on the surface of nanoparticles, thus inhibiting the reaction. The entire analysis provides a new perspective to study the catalytic mechanism and evaluate the catalytic activity of the peroxidase‐like nanoparticles.